Long chain saturated aliphatic amino acids, lactams, and dibasic acids are important monomers for long chain nylons and engineering plastics. Nylons are a class of polymers that contain amide bond on their backbone of chains. Nylons are one of the most widely used, most numerous in types, and most consumed class of engineering plastics.
Because of their unusual molecular structure, long chain nylons possess extraordinary physical properties, i.e., higher mechanical strength than metal, low hygroscopicity, excellent resistance to oil, low temperature, abrasion, and chemical corrosion, and most importantly, easy to fabricate. Long chain nylons are made into many kinds of plastics products, spun to fibers, and stretched to thin films. Long chain nylons are also used in paints and hot melt adhesives. Hence, long chain nylons find wide applications in automobile, electrical, electronic, telecommunications, petrochemical, and aerospace industries.
Long chain amino acids and lactams are used industrially as monomers to produce nylon-9, nylon-11, and nylon-12.
Long chain dibasic acids are condensed with diamines industrially as starting materials to produce nylon-610, nylon-612, nylon-510, nylon-512, nylon-1010, and nylon-1212.
WO 2017/088218, the co-pending U.S. Ser. No. 15/601,556, and U.S. Ser. No. 15/644,708, all of which by the present inventor, disclose a novel process for the coproduction of long chain amino acids and dibasic acids from keto fatty acid derivatives. According to these prior art, long chain keto fatty acid derivatives are reacted with hydroxylamine to form an oxime derivative, which is subjected to the Beckmann rearrangement to yield a mixture of two amide derivatives. These amide derivatives are hydrolyzed with an acid or a basic agent to a mixture of products containing long chain amino acids and dibasic acids, which are isolated by a process of step-wise neutralization. The hydrolysis is carried out with an alkali hydroxide as the hydrolysis with an acid is extremely slow and takes excessively long time to complete.
Copending application U.S. Ser. No. 15/635,874 discloses a process for the complete separation of each component from a mixture of the hydrolysis products in the production of long chain dibasic acids and amino acids without discharging any waste aqueous stream.
The process according to WO 2017/088218 and U.S. Ser. No. 15/635,874 makes use of an alkali hydroxide, most preferably sodium hydroxide, and an acid, most preferably sulfuric acid, to accomplish the production and separation. As a result, a large amount of sodium sulfate is generated in the production process. As a byproduct, sodium sulfate is costly to form from sodium hydroxide and sulfuric acid. In addition, sodium sulfate is of little value and is increasingly difficult to dispose of.
It is an object of the present invention to disclose a process for the production of long chain amino acids and dibasic acids by performing the hydrolysis of mixed amide derivatives with ammonia or ammonium hydroxide.
It is another object of the present invention to disclose a process for the separation of each component from a mixture of the products by the ammonium hydroxide hydrolysis. According to the process of the present invention, long chain amino acids and dibasic acids are produced and separated simply, efficiently, and economically with high yields and excellent purity. The only byproduct is ammonium sulfate, which is a valuable commodity as a fertilizer.